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Figure 1. Schematic diagram of limnological processes taking place in Kandy lake during high and low water levels.
A. granulata and P. simplex) reestablished themselves with several minor species such as non-nitrogen fixing cyanobacteria, Merismopedia punctata. Although M. aeruginosa appeared throughout the following years, it did not form a bloom as in the previous year. The most likely limnological interpretation for the sudden emergence of M. aeruginosa is as follows. The lowering of the water level during the dry spell of 1999 may have resulted in greater access for M. aeruginosa to utilize phosphorous mobilized in the anoxic deeper layer, as shown in Figure 1. It is known that Microcystis shows good buoyancy; it comes to the surface and drifts along the wind
direction. The schematic model shown in Figure 1 and the available limnological information clearly demonstrate that the biomass regulation or prevention of emergence of Microcystis biomass in Kandy lake is a combination of both top-down and bottom-up approaches11. Multiple techniques may also be relevant in the case of restoration, since the urban lakes are different from other man-made water bodies1. Nevertheless, sound knowledge of hydrology, limnological processes and dynamics of the water body and the human activities taking place in the watershed plays a key role in restoration and management.
1. Annadotter, H., Cronberg, G., Aagren, R., Lundstedt, B., Nilsson, P. and Ströbeck, S., Hydrobiologia, 1999, 395/ 396, 77–85. 2. Lammens, E. H. R. R., Hydrobiologia, 1999, 395/396, 191. 3. Pilaou, E. C., Fresh Water, The University of Chicago Press, 1998, p. 175. 4. Lewis, W. M., Water Resour. Res., 1981, 17, 169–181. 5. Silva, E. I. L. and Schiemer, F., ACIAR Proc., 2001, 98, 215. 6. Schiemer, F., Amarasinghe, U. S., Frouzova, J., Sricharoendham, B. and Silva, E. I. L., ACIAR Proc., 2001, 98, 111. 7. Talling, J .C. and Lemolle, J., Ecological Dynamics of Tropical Inland Waters, Cambridge University Press, Cambridge, 1998, p. 441. 8. De Silva, P. K. and De Silva, K. H. G. M., Archaeol. Hydrobiol., 1984, 102, 53. 9. Dissanayake, C. B., Semaratne, A., Weerasooriya, S. V. R. and De Silva, S. H. G., Environ. Int., 1982, 17, 343. 10. Dissanayake, C. B., Rohana Bandara, A. M. and Weerasooriya, S. V. R., Environ. Geol. Water Sci., 1986, 10, 81. 11. McQueen, D. J., Johannes, M. R. S., Post, J. R., Stewart, T. J. and Lean, D. R. S., Ecol. Monogr., 1989, 59, 289.
Received 5 January 2003; revised accepted 25 June 2003
E. I. L. SILVA Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka e-mail:
[email protected]
Cadra cautella Walker (Lepidoptera: Crambidae: Phycitinae) – a pest on Parkia timoriana (DC.) Merr. in Manipur Among the numerous less familiar food used by the local communities in northeast India is a tree legume, commonly known as tree beans (Parkia timoriana) or yongchak by the locals in Manipur. The tree bean, P. timoriana (DC.) Merr. syn. P. roxburghii G. Don belongs to the family Leguminosae and sub-family Mimosoideae1. It is one of the most
common multipurpose trees in Manipur having high commercial value, and is commonly grown in the backyard of houses, jhums and forests throughout Northeast India2. It flowers during the months of September–October and the onset of fruiting starts from November onwards. The pod is available from November till April, and is consumed in
CURRENT SCIENCE, VOL. 85, NO. 6, 25 SEPTEMBER 2003
all its developmental stages starting from the green, tender pods to the matured, black seeds, fresh or cleaned and sundried for future use during the offseason. The associating pungent smell in the seeds is due to the presence of thiazolidine-4-carboxylic acid (TCA, thioproline), a cyclic sulphur-containing amino acid3 . Thioproline is known to be 725
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a
b
c
d Figure 1. a, Pupation inside infested seed; b, Adult moth; c, Larva infesting inflorescence head and d, Infested pod head.
anti-carcinogenic and inhibits the formation of squamous cell carcinomas in the fore-stomach of rats4,5 . A number of workers have reported the biochemical and nutritional values of the plant, including various medicinal uses6–12 . During the months of June–July 2000, heavy infestation of caterpillars of Cadra cautella was observed on stored treebean seeds in properly sealed paper bags at Imphal (782 m above sea level), Manipur. These seeds were stored in April, after proper drying. Literature survey revealed few reports of pest infestation on Parkia spp. The pod-boring larvae of the pyralid moth, Mussidia pectinicorella
726
Hamps. and torticid moth, Argyroploce illepida Btlr. infest the ripening seeds of P. speciosa, while M. nigrivenella Ragonot is a natural pest on P. biglobosa13–15. However, there is no record of C. cautella infesting tree beans. The larvae of C. cautella feed voraciously on the green kernels. The larvae are elongated caterpillars, about 2 cm, grayish-white with numerous dark setae interspersed along the body. They are mobile and make webs as they tunnel through the food, and excrete yellowishbrown excreta near the point of entrance. The duration of larval stages was between 45 and 60 days. The larvae start feeding from the surface of the kernels and continue inside. In the case of heavy infestation, the whole kernel from the inside was consumed, while the outer skin of the seed had tiny holes through which the larva entered. Each seed bore only one larva. It caused considerable amount of damage in the infested seed, rendering it unfit for consumption. Pupation occurred inside the crevices of the infested seeds and the paper bags (Figure 1 a). The pupa is reddish-brown, immobile, produces large webs and is enclosed in a cocoon. The adult moth appears after two weeks of pupation. Adult moths are mottled grey, fawn-coloured with a fringe on the back of each hind wing (Figure 1 b). They do not feed. They fly in the early morning and late afternoon. They are short-lived, surviving for approximately twelve days. Adults spread infestation through eggs laid in the bags and on seed surfaces. Immature dropping of inflorescence and pod heads during the months of October to February were found to be associated with larval infestation. The dissection of these heads revealed the larvae making extensive damage inside (Figure 1 c and d). Thus it was observed that C. cautella infested the plant, both in the field and on storage. All the stages in the life cycle of the insect were observed on P. timoriana. 1. Hopkins, H. C. F., Kew Bull., 1994, 49, 198–199. 2. Kanjilal, U. N., Kanjilal, P. C. and Das, A., Flora of Assam, Avon, Delhi, 1982, vol. 2, p. 151.
3. Suvachittanont, W., Kurashima, Y., Esumi, H. and Tsuda, M., Food Chem., 1996, 55, 359–363. 4. Tahira, T., Tsuda, M., Wakabayashi, K., Nagao, M. and Sugimura, T., Gann, 1984, 75, 889–894. 5. Tahira, T., Ohgaki, H., Wakabayashi, K., Nagao, M. and Sugimura, T., Food Chem. Toxicol., 1988, 26, 511–518. 6. Burkill, I. H. (ed.), A Dictionary of the Economic Products of the Malay Peninsula, Ministry of Agriculture and Cooperatives, Kuala Lumpur, 1966, 2nd edn. 7. Quisumbing, E., Technical Bulletin, Dept. of Agriculture and Natural Resources, Manila, 1951, no. 16. 8. Sharma, B. D., Hore, D. K. and Salam, J. S., Indian J. Plant Genet. Res., 1993, 6, 171–173. 9. Salam, J. S., Khuman, M. S. and Singh, M. P., Curr. Sci., 1995, 68, 502. 10. Salam, J. S., Agric. Sci. Digest, 1996, 16, 189–191. 11. Mohan, V. R. and Janardhanan, K., Int. J. Food Sci. Nutr., 1993, 44, 47–53. 12. Longvah, T. and Deosthale, Y. G., Food Chem., 1998, 62, 477–481. 13. Kalshoven, L. G. E., The Pests of Crops in Indonesia (revised and translated by van der Lann, P. A.), Ichtiar Baru-van Hoeve, Jakarta, 1981. 14. van der Goot, P., Dierlijke vijanden van djengkol en peteh, Meded, Algem. Proefst. Landb., 1940, no. 46. 15. Setamou, M., Schulthess, F., Gounou, S., Poehling, H. M. and Borgemeister, C., Environ. Entomol., 2000, 29, 516–524.
ACKNOWLEDGEMENT. We thank M. Shaffer, The Natural History Museum, London for identification of C. cautella moth and larva.
Received 10 June 2002; revised accepted 15 July 2003
R OBERT THANGJAM M. DAMAYANTI* G. J. S HARMA Department of Life Sciences, Manipur University, Imphal 795 003, India *For correspondence. e-mail:
[email protected]
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